This story is told in Nikolai Arsenic’s book, Mysticism in the East:

Comrade Lunachatsky was lecturing in Moscow’s largest assembly hall shortly after the Bolshevik Revolution. His theme was, “Religion: Opium of the People.” All the Christian mysteries are but myths, he said, supplanted by the light of science, Marxist science is the light that more than substitutes for the legends of Christianity. Lunachatsky spoke at great length. When he finished, he was so pleased with himself that he asked if anyone in the audience of some seven thousand had anything to add. A twenty-six-year-old Russian Orthodox priest, just ordained, stepped forward. First he apologized to the commissar for his ignorance and awkwardness. The commissar looked at him scornfully: “I’ll give you two minutes, no more.” “I won’t take very long,” the priest assured him. He mounted the platform, turned to the audience, and in a loud voice declared, “Christ is risen!” As one man the vast audience roared in response, “He is truly risen!”.

May your heart and mine rejoice in the fact of His glorious resurrection!

He is Risen! He is Risen indeed!